I was running 4.3.2 carbon rom and got a full 4 bars of lte every where on my school's campus. I "upgraded" to 4.4.1 via cm11 then 4.4.2 via vanir Rom over the weekend. The phone was super fast and responsive, but when I got back to school, I only had maybe one bar of lte for like a second, then an intermittent 2 bars of 3g. So I switched back to my backup, to take a backup of my old apns to restore on the kitkat Rom . The same thing is happening. I flashed 3 different modems, including one that I'm sure is the modem I was using previously, and I'm running the same Rom I was using. What the hell happened?

Edit: if it matters, I'm in dc, and I'm referring to udc.

Edit 2: I have better signal in and around my house, but I have Wi-Fi around my house, I need lte around school.

I'm not familiar with CM but I'm surprised there's no way to update PRL and profile. Checked the CM for Sprint thread on XDA, and it appears that in order to update PRL you need to flash a TW ROM, update PRL, then reflash CM. Not exactly CDMA friendly.

You could call Sprint, give them your MEID, and ask them to re-provision your phone (that's what the 72786 code does normally.) That process will update the PRL, too. On a TW based ROM, at least.